Computation of the Noise Intensity (and the Noise Reduction) of an Electrical Fan

Computation of the Noise Intensity (and the Noise Reduction) of an Electrical Fan

By Yi-Ting Hsu
MASTER DEGREE OF ENGINEERING
DEPARTMENT OF Mechanical Engineering
NATIONAL TAIWAN UNIVERSITY
June 2005
ADVISER: Dr. Jia-Yush Yen
Reducing acoustic noise from rotating machinery is always desirable to all the applications. To estimate the noise level generated from rotating machinery, on the other hand, is very difficult. The computation often involved the interference between structural vibration and the induced air flow. The noise may result from both the flow field and the structural resonance. From the computation point of view, the moving part of the rotating machinery also requires additional treatment. This thesis addresses the modeling of the handsaw noise. The high speed handsaw uses a fan attached to the rotor to remove the heat accumulation. This thesis uses the Ffowcs-Williams/Hawkings formulation in Fluent to analyze the acoustic Sound Pressure Level (SPL). The analysis compares the simulation frequency spectrum with the experimental measurement and provides suggestions for noise reduction.